Method and device for recovering a wanted acoustic signal from a composite acoustic signal including interference components

Abstract

The device for extracting a useful acoustic signal from a composite acoustic signal including nuisance components includes: first sensor component for picking up the composite acoustic signal; second sensor component for picking up, in real-time, the reference acoustic signal, which is substantially correlated with the nuisance components of the composite acoustic signal; adaptive filtering component; and extraction component. The coefficients of the filtering component are adapted in real time according to an algorithm chosen so as to minimize the energy of the composite acoustic signal as a function of the energy of the reference acoustic signal, until the signal leaving the output of the extraction component corresponds substantially to the useful acoustic signal selectively rid of the nuisance components.

We claim: 
     
       1. A device for extracting a useful acoustic signal (Un) from a composite acoustic signal (Mn) comprising nuisance components (Pn), the device being one which comprises: first sensor means (2), which are arranged at a first chosen location and are able to pick up the composite acoustic signal (Mn),   second sensor means (16), which are arranged at a second location chosen according to a predetermined geometric relationship with the first location, and are able to pick up, in real time, a reference acoustic signal (Rn) which is substantially correlated with the nuisance components (Pn) of the composite acoustic signal (Mn) and is capable of propagating from the said second location to the said first location,   filtering means, of the adaptive type, (12) possessing a first input (14) linked to the second sensor means (16), a second input (15) and an output (17), and   extraction means (6) possessing a first input (4) linked to the first sensor means (2), a second input (8) linked to the output (17) of the filtering means (12), and an output (10) linked to the second input (15) of the filtering means (12), wherein the second location is chosen so that the reference acoustic signal (Rn) contains no information related to the useful signal (Un) and wherein the filtering means (12) are able to minimize the energy of the composite acoustic signal (Mn) as a function of the energy of the reference acoustic signal (Rn), by adapting at least some of the filtering coefficients in real time, until the signal (Sn) leaving the output (10) of the extraction means (6) corresponds substantially to the useful acoustic signal (Un) selectively rid of the nuisance components (Pn).   
     
     
       2. The device as claimed in claim 1, wherein the extraction means (6) are summator means of the analog type, wherein it furthermore comprises an acquisition stage comprising first analog/digital acquisition means (18), possessing an input (20) linked to the second sensor means (16) and an output (22) linked to the first input of the adaptive filtering means (12); and second analog/digital acquisition means (36), possessing an input (38) linked to the output (10) of the analog summator means (6) and an output (40) linked to the second input (15) of the adaptive filtering means (12), and   wherein it furthermore comprises a restitution stage comprising first digital/analog restitution means (32), possessing an input (30) linked to the output (17) of the adaptive filtering means (12) and an output (34) which delivers a signal (An) applied to the second input (8) of the analog summator means (6).   
     
     
       3. The device as claimed in claim 1, wherein the extraction means (6) are summator means of the digital type; wherein it comprises digital processing means (100) possessing first (4), second (14) and third (15) inputs, and an output (10), the said digital processing means (100) being able to carry out the functions of the digital summator means (6) and of the adaptive filtering means (12),   wherein it furthermore comprises an acquisition stage comprising third analog/digital acquisition means (118), possessing an input (120) linked to the first sensor means (2) and an output (122) linked to the first input (4) of the digital processing means (100); and fourth analog/digital acquisition means (136), possessing an input (138) linked to the second sensor means (16) and an output (140) linked to the second input (14) of the digital processing means (100).   
     
     
       4. The device as claimed in claim 3, wherein it furthermore comprises a restitution stage comprising second digital/analog restitution means (132) possessing an input (130), linked to the output (10) of the digital processing means (100), and an output (134). 
     
     
       5. The device as claimed in claim 1, wherein the digital filtering means (12) are of the digital signal processor type and wherein the minimization algorithm is of the least mean squares type. 
     
     
       6. A process for extracting a useful acoustic signal (Un) from a composite acoustic signal (Mn) comprising nuisance components (Pn), the process comprising following steps: a) providing first sensor means (2), which are arranged at a first chosen location and are able to pick up the composite acoustic signal (Mn),   b) providing second sensor means (16), which are arranged at a second location chosen according to a predetermined geometric relationship with the first location, and are able to pick up, in real time, a reference acoustic signal (Rn) which is substantially correlated with the nuisance components (Pn) of the composite acoustic signal (Mn) and is capable of propagating from the said second location to the said first location,   c) providing filtering means (12), of the adaptive type, possessing a first input (14) linked to the second sensor means (16), a second input (15) and an output (17), and   d) providing extraction means (6) possessing a first input (4) linked to the first sensor means (2), a second input (8) linked to the output (17) of the filtering means (12), and an output (10), the said process being one wherein the second location is chosen so that the reference signal (Rn) contains no information related to the useful signal (Un), and wherein it comprises a step consisting in:   e) minimizing the energy of the composite acoustic signal (Mn) as a function of the energy of the reference acoustic signal (Rn), by adapting at least some of the filtering coefficients in real time until the signal (Sn) leaving the output (10) of the extraction means (6) corresponds substantially to the useful acoustic signal (Un) selectively rid of the nuisance components (Pn).